WO2013011449A4 - Flat conductors, their manufacturing and principal uses - Google Patents

Abstract

The invention regards flat (strip) electric conductors made out of copper or aluminum, with suitable width and thickness for home and automotive uses. The lead strips are insulated by covering them with a thin insulating foil out of a hard plastic with high dielectric strength, so that it has despite the small thickness sufficient flexibility to be fixed once and to stay there. The fixing is done by bonding on a support. (a wall, a car body). Fig. 1 shows a comparison between the new insulated strips and the state of the art conductors with wire leads.

Description

FLAT CONDUCTORS, THEIR MANUFACTURING AND PRINCIPAL USES.

The invention relates to conductive flat leads (strips) of copper or aluminum, with appropriate width and thickness made of materials suitable with good electrical properties. The lead strips are isolated by covering them with a thin insulating film of a plastic having high dielectric strength and rigidity and due to their small thickness do have enough flexibility to be fitted once and to stay there as mounted. These materials are commonly used in electrical motors and transformers as insulation or as dielectric for capacitors. Typical materials for insulating films with excellent properties are polyethylene terephthalate, polybutylene terephthalate, polyester film (Mylar) or Polyethylene Naphthalate (PEN, Teonex ®) or polystyrene, polypropylene, etc. .. with typical thicknesses between 16 - 50µm. For special purposes materials like Nomex Kapton etc. ..are also used.

Prior art. Similar conductors are known in the art and also products for example from U.S. firm Alphacore (U.S. patent application 07/944, 835) or Synflex in Germany, but they are being used for other purposes than those set forth in this invention. By their manufacturing process, they are inferior to the product according to this invention and have thicker insulation due to overlapping foil edges needed to stick them, or a considerable increase in width of the insulated strip by more than 2x1mm compared to the lead strip width for the same reason. In many of the modern office machines, flexible flat strip cables are build-in, they being produced with special heat –bonding insulation foils which, due to their special two-layer structure are more expensive and not available in very thin dimensions. In addition, bonding is not sure and sturdy as welding. These conductors are used for small technical fields such as separation of transformers windings, shielding, etc ... The lead strips and insulated strips according to the invention present a certain geometric resemblance with the winding bars for high power motors and transformers, but all of very different sizes, made with a new technology and used for different purposes. The Aim

The aim of the present invention is to show how, through a smart combination of conductor strips with various plain and inexpensive insulating foils and adhesives, insulated strips and flat cables with good properties can be made which can replace fixed or semi-mobile wiring cables used in electrical fields. Many conductors used in the state of the art can be replaced with the present flat conductors as in this invention, eg distribution cables in homes and industrial buildings, as in the electrical systems of automobiles, airplanes, ships, etc. The preferred fixing of a flat cable on a support will be done through adhesives, as it is done with the adhesive tapes. By reducing the very high volume of insulating stuff used with round conductors and practically eliminating the air space between conductors, new opportunities arise using new aluminum cables according to the invention, having the same electrical qualities but a smaller volume and weight compared to round copper cables. Another aim of the invention is to show how to achieve with advantage the replacement of today usual copper cables (expensive) with aluminum flat cable (easy, cheap), with obvious economic advantages, especially in the automotive and aviation industry, for the wire harness. One of the main advantages of the invention is that the amount of insulation used is much lower than with conventional solutions. By this, both the cross-section of the cable and fire hazards or harmful fumes emanation are greatly reduced having also much improved heat dissipation.

Indicative examples: We will consider three variants of cables having 20 leads each with a resistance of 11mOhm/m, which include: a) usual copper wire, stranded and insulated, b) 36µm Mylar insulated copper strips and c) 36µm Mylar insulated aluminum strips, s. the table below: The total cross-section with insulation, 20 leads, in mm² is calculated from the cross-section of every insulated conductor, with different space factors from 0,8 for round leads and 0,96 for flat strips, these last giving an almost compact bundle with very little air spaces. Of course, the cross section of the aluminium flat strip is with 2,4 mm² higher than that of the copper leads (1,5 mm²) , to insure the same resistance.

Constitution	Leads	Metal cross- section, mm²	Total cross- section with insulation, 20 leads, mm²	Metal fill factor	Weight, g/m
Round cable, Cu-wire stranded	20	20x1,5 =30	20x7,5x/0,8 =187	30/187 =0,16	400
Cu- strip cable, Mylar insulated	20	20x1,5 =30	20x2,14x0,95 =45	30/45 =0,66	280
Al- strip cable, Mylar insulated	20	2,4x20 =48	20x3,2x0,95 =67	48/67 =0,71	150

Fig. 1 shows the difference in the needed space and the weight per meter in the three variants of cables shown above, having 20 conductors à 11mOhm/m. The advantages of using thin insulated lead strips are evident. The Mylar foil insulation withstands at least 3 kV, and at temperatures much higher than the regular PVC insulation. It is therefore clear that a replacement of the wire harness in automobiles or aircraft with wire harnesses made out of insulated strip or flat cables as in this invention is conceptually superior with respect to the space needed and weight. Savings, weight and cross- section diminution and results more clearly by using aluminum, cross- section and weight are reduced by more than 60%, as seen above. Aluminum wire harness (but of a "classic" kind) are already used in the Airbus 380.

The advantages of flat strip lead technology are:

- Heat dissipation area is larger, especially for cables with few insulated strips 3,

- The heat transfer is largely improved with complex flat cables 4, because of the contact surface and of the performing thin insulation, and based of this,

- the permissible electrical load is increased,

- Practically no risk of fire, the small amount of insulation of the lead strips providing for self- extinguishing properties,

- In case of short circuits the toxicity is greatly reduced due to the self- extinguishing capacity, to the thin insulation and reduced output of toxic gases, please see more under “thermal properties”. In special cases (vehicle industry) the use of flat cables can even contribute to noise deadening with structures on which flat cables are bonded on, see “other advantages”

- Quick and easy fixing,

- Easy manufacturing on relatively simple and energy saving machines with zero or very small release of pollutant stuff,

- Low costs due to the use of aluminum,

- Low start-up investment and quick payback,

- Lightweight,

- Shielding effect and diminution of the voltage transients due to the relatively large distributed capacity. Despite the thin insulation, the mechanical behavior of the flat cable 4 is unexpectedly good. This happens because the insulation, although thin, has mechanical properties close to these of aluminum and copper as it is used for the lead strips 1. If one knocks, for example, an electrical common cable with a hammer, the copper conductors will "cut" the soft PVC insulation, so that a short-circuit occurs. For the flat cable 4, such a blow would often simultaneously lead to a local flattening of both the lead strips 1 and of the foils 2 but not break them, so that this usually does not lead to a short-circuit.

Definitions: A flat metal conductor, insulated according to the invention will be hereinafter referred to as a lead strip 1. The lead strip 1 will be isolated with an insulating film (eg. Mylar), defined as the foil 2. A lead strip 1 or more stapled lead strips 1 coated by the foil 2 will be called insulated strip 3. An assembly of at least two reciprocally insulated strips 1, 3, is called flat cable 4, whereby its insulated strips 3 will get according to their use supplementary appellations. The flat cable 4 can be fixed preferably by gluing on a support 5 (wall, car body, etc.. with a mounting adhesive 14. Depending on the number of the lead- 1or insulated strips 3 the flat cables 4 can have two, three or more current paths. Some of the lead strips 1 may not have their own insulation, being still insulated from the insulated strip 3.

Making of insulated strip, Fig. 2. According to the invention, the disadvantages of the prior art, so the use of a large amount of insulating stuff (especially with the round cables, used almost at 100%) are avoided through a special process of welding a foil 2 around a lead strip 1 along its edge, so that the excess width does not exceed 0.2 ... 0.8 mm. The maximum size of a lead strip1 that will be ca. 0.25mm thick and ca. 10 mm wide. A multitude of welding proceedings of thermoplastic foil are known in the art by heating, usually by contact with hot surfaces, hot wire, these usually having coatings (eg. Teflon) that prevent sticking of the plastic on hot surfaces. Despite this it is difficult to avoid soiling from the material melted or decomposed, welding very thin foils (less than 30µm) is practically impossible. Another disadvantage is that often the obtained welds are not smooth, they are rough, often the molten material pulling "whiskers", etc ... According to the invention, this is avoided by melting locally, without contact the edges of the foil 2 which can so be welded by heat radiation effect, what makes possible an effective, continuous production. For a perfect enveloping of the lead strip 1, the foil 2 can be heat- shrunk after the weld with subsequent cooling; (most of the foils 2 shrink 2-10% after heating), some can be shrunk by chemical means, eg. with solvents. You can also use special foils, which shrink more after heating-cooling. In order to avoid corona discharges without filling the sometimes unavoidable small air spaces with silicone gel 16 (for example, for the insulated strip 3, as well as for the flat cable 4) one can use metal- coated foils 2 or antistatic treated on one or both sides. They will have resistances per square in the megaohm range. The characteristics of the materials used may be, by necessity, for example the following: Between lead strips 1 and foils 2 an inside adhesive film 15 is applied which usually will be of electrical quality, resins or rosin varnish, whereby this helps to make soldering the connection of link cables easier. Tinning can be done directly through the foil 2 (Mylar for example), it melts under the action of the soldering iron, which then acts directly on the copper lead strip. The inside adhesive 15 can be dispensed so that the bonding to the lead strips is more or less strong, (from 0-, no adhesive, till full surface bonding), this being often important for the stripping of the foil 2 at the ends. A variant is the one-side bonding, so that the side with no adhesive can be very simply stripped out. You can choose solvent based, fluidised inside adhesives 15 whereby the solvent can be partially or totally removed by diffusion through the foil 2, even during the shrinking process. The cables can be delivered for example in sealed packages, the adhesives used can be maintained in the still plastic state by a residual solvent, to facilitate folding and assembly. Because of the slow evaporation of the remaining solvent, the cables will further stiffen after fixing. The thickness of the inside adhesive 15 can be set even below 1µm. This avoids the thickening of the insulated strip, 3, as it occurs at the prior art. Thin foils, adhesives and surface coatings can be very difficult to represent graphically, so we try to describe them accurately in words. To facilitate understanding of the invention, Fig. 2 shows how an insulated strip 3 is being done. It is made of lead strip(s) 1 and a foil 2 of a width more than double, which was brought by guides to fit around a lead strip 1, so that their edges are adjacent. In this position the edges of the foil 2 are locally heated till melting in the heating zone 43, where they touch together so that a weld occurs. By using thermoplastic foils with thicknesses typical of the 16 - 50µm, they will give a very strong weld with a weld bead 44 which is only minimally thickened. Fig. 3 shows how to achieve the simultaneous isolation of several (3) metal lead strips 1, placed parallel and laterally offset in the same plane, spaced the intermediate spaces 18. The lead strips 1 (a, b, c) advance lengthwise (out from the drawing) with a constant speed equal to the speed of two insulating foils 2a, 2b which are guided to a small gap (they can touch together) up and below the lead strip 1. The foils 2a, 2b exceed the total width of the lead strips 1, by the intermediate spaces 18 between them plus a convenient surplus 19 on both outer sides. In the areas 18 and 19 sources of radiation 21, (infrared, laser, etc..) will be located and well-focused, at the one or both sides (bottom and top), which will lead to the local softening or melting of the foils 2a, 2b. They will be brought into contact in the areas 19 and 18 and as they advance, they will be subsequently cooled, thus remaining welded along the desired line. For bringing the foils to be welded in contact, one can use rollers or a pressure difference between inside (where the lead strips 1are) and the outer space, in which a bigger (air) pressure will be present. To facilitate the melting- welding process, in the areas 19 and 18 one can dispense small amounts of substances absorbing the radiation 22, which can be distributed as known from an inkjet printer. In the melting-welding zone of the foils 2a, 2b, a narrowing of the plasticity zones 19 (convenient surplus) and 18, (intermediate spaces) may occur and so the total width of the insulated lead strips 3 which become a flat cable 4, produced in one operation will be reduced. Between lead strips 1 and foil 2 inside adhesives 15 may be applied. What is described in Figure 2 and 3, how the lead strips 1 are insulated, is also valid for the insulated strips 3 as well as for the flat cables 4, where a foil (2) is used, which cannot be welded by direct heating. In this case, welding and gluing them will be achieved by the addition of stuff that leads to the creation of a seam closing tightly.

Flat cable 4-, manufacturing. In order to produce the flat cables 4 out of the insulated strips 3 according to fig. 2 and 3, they are put together and can be assembled by point- or continuous bonding, wrapped in other foils, closed into a tube, or the inclusion in a semi-rigid intermediate adhesive 24 mass (resin, silicone gel). The actual adhesive technology offers thousands of solutions. We call the substances used here as an intermediate adhesive 24. They can have for instance very different or permanent elastic properties to allow bending of cables, filling the remaining space in the corners, etc ... At the place where the flat cables 4 are fixed (on a support such as wall, a vehicle body, the wall of an electrical distribution box), we can use mounting adhesives 14 and we call this step as fixing adherence. This can be done with known mounting adhesives 14 (self-sticking, eg. based on acrylic resins, rubber, etc.), dispensed at the manufacturing and then covered by a protective tape 20, which is taken off just before fixing. In the manufacturing process, the adhesive paste can be first dispensed on the protective tape 20 (silicone paper) and then transferred with it to the flat cable 4. A special case is the bonding on dust- making supports 5, where the use of an appropriate primer for the mounting adhesive 14 can become a must. The sticking fixture can also be realized in full subsequently, for example the cable harness of a vehicle can be glued in the car assembly factory, by mounting adhesives 14, this assembly being specific to that industry, dispensed as hotmelts or pastes. The insulated strips 3 or the lead strips 1 placed outwards to the support 5 shall be used as a rule as shielding or grounding strips and placed on the opposite side with respect to the cable support. To fulfill the aims of the invention, modes of making and blending of the technical solutions are presented to get the flat cable 4 complex, out of copper and / or aluminum lead strips 1, as well as flat power cables 4 for single- and three phase networks, for automotive, aircraft, etc. ... Fig. 4 represents the cross section thereof. The number of flat strips as Fig. 4, can vary between 1 and n (more). We present three main variants A, B, C of combination of insulated strips 3 in order to build flat cables 4. For more complex structures, such as for example wire harnesses for cars or planes we can combine variants like A, B, C, comprising ready flat cables 4 as required. So in all these variants we can multiply the number of insulated strips 3 in upright or horizontal extent consistent to the purpose. In the A variants, three piled- up insulated lead strips 3a, 3b, 3c are held together by a mantle 23. Inside the mantle 23, the insulated strips 3 can be glued together or not, or the spaces between them are filled with an intermediate adhesive 24 which can be a gel sealant (and gluing) to prevent corona discharges. The mounting adhesive 14 is applied on one side of the mantle 23. In the B variant (here as a three-phase cable, for example) the four insulated lead strips 3a, 3b, 3c, 3d (which may be done simultaneously as shown in fig. 3) are placed in the same plane and surrounded by a fifth cover insulated strip 3e, which, being wider shields them, replacing the mantle 23 of the previous case and will usually be linked to the potential 0 "earth". In the C version, which can be made very thin, the insulated strips 3a, 3b placed side by side will be glued to the lead strip 1 which is wider, without insulation, or to an insulated strip 3, with an intermediate adhesive 24 and below, to the support 5 we will apply an mounting adhesive 14 which extends on the outer edges of the strip 1 or of the insulated strip 3. Also the strips (1or 3 as appropriate) opposite to the substrate 5 will keep the other two below it (thus replacing the mantle 23) and lead to a stepwise increase of the thickness (see fig. 4) so that the flat cable is not only thinner (at the same parameters) than the others but also lighter. The upper strip will act as a shield and at line applications it will compulsory be linked to potential 0 (ground). A special case of the variant C, which will often occur in practice is a cable having only two insulated strips 3, these being kept on the support 5 only by a broader common, non conductive adhesive tape instead of the shielding lead- 1 or insulated strip 3. Special designs: in order to insure the needed flexibility, for example in transitions to the door of a car, more very thin (e.g. 0,05mm) lead strips 1 can be stacked to get an insulated strip 3. In other special cases, (such as electrical harness of an electric bike with visible tubular support frame), the use of a “hidden” flat cable are special suitable. The Figure 11 shows more, on the tubular support 5´ around distributed insulated strips 3. These cling to the support 5', so that they can be tucked inconspicuously under a protective or decorative coating, which is applied or sprayed. The linking of the insulated strip 3 can be ensured with a round clamp, which has contact points on the inside.

Thermal properties. The parallel, flat gap between the lead strips 1 and the support 5, through the mounting adhesive 14 (this can be a heat transmitting one) can be as thin as 0,1mm, so this offers a good heat transmission opportunity. An outstanding capability (not present at the state of the art) is the capacity of the insulated strips 3 or flat cables 4 to almost completely sink the heat, which arises with the current passing to the support 5, if this has a good thermal conductivity (metals). This can advantageously happen e.g. with car or plane bodies. Even if the nominal current capacity is 10-fold exceeded, the correct thermally coupled flat cables 4 will stay below 100°C and cannot cause fumes or even fire, as the usual cables do! The reduced fire hazard can save lives. The heat can even be removed both sides, if a flat cable 4 is placed between two heat sinking surfaces, e.g. between two metal sheets, but gives new opportunities for the “lean” design of flat cable harnesses.

Other advantages: The stuck flat cables 4, properly designed can also lead to more advantages: Broad power flat cables (4) stuck e.g. on the inner wall (support 5) of a fighter plane fuselage can not only be highly overloaded, but they can also resist shelling, as they will not break, but only be punched and be by proper design self-healing. Another property of the broad flat cables 4, stuck on a vibrating (drumming) support 5 can considerably reduce this noise, as they form with the support 5 and the viscous- elastic mounting adhesive 14 an noise suppressing sandwich.

Bendings, bifurcations, plugs, switches, apparatus. The linking of the flat cables 4 with existing plants raises the question of bending and connecting them to existing equipment (made for the usual cables) and possibly connecting them to new devices specially designed for this purpose. In their design and implementation, an essential property of insulated lead strips 3 (and thus flat cables 4) must be taken into consideration, namely their high flexibility in the thickness direction and a very low flexibility in the width direction. To make sideways or upright bifurcations and exits from the lengthwise direction, it is needed to make bending and folds where possible, also in the thickness direction (Fig. 5). Fig. 5a shows a simple folding of a single strip, but this principle also applies to the flat cables. A flat cable 4, used for home electrical installations, for example, consist of three insulated strips, 3N, 3F and 3P. The 3P insulated strip will be placed above (outside, protecting the other two), but after a simple folding 25 as in Fig.5, the insulated strip 3N will appear above instead of 3P. To avoid this, you can perform as shown in Figure 5b a second fold, thus resulting in the double fold 26, whereby the order of stacking in the height of the three insulated strips 3 will appear identical. To best understand these issues, anyone can bend a strip of paper, seeing intuitive possibilities and limitations. The double folding 26 of Fig. 5b consists of a simple folding first 25 to the right 90 ° (a) followed by a second fold to 180 ° to the left (b). So, for practitioners the first fold will be in the contrary direction of the finally desired, the first fold being after that "covered" by the second fold to 180 °, so the double folding 26 will result in the desired direction. Both types of folds (Fig. 5 and 5b) can be made in different convenient angles than as it is drawn. These folds will be used not only with insulated strips 3, but also in flat cables 4 or for bifurcations of more complex flat cables 4 (wire harness of a car). In making any bifurcations or link heads, plugs, etc., the characteristics of folding must always be taken into consideration. Although at the first glance bending flat cables 4 seems more complicated, from the viewpoint of automation and fixing on a support 5 there are important advantages: - An automatic folding is very simple and will produce layouts with side stiffness, (precise, flat layouts); - Because of this, the machine which fixes the flat layouts on the support can be simple, because instead of flexible cables "restive to stay at the right place", "a mechanical hand" will find "blind" laterally rigid side strips perfectly placed in space. These are very important benefits for big series industries (automotive). In terms of achieving links between cables (with plugs or similar) we will make references to plugs made of an aluminum strip (these issues are more complicated). What we describe can be (easier) applied for strips of copper or alloys. The simplest type of connection between flat cables 4 is "strip head to strip head", which is similar to the eight fingers of two hands alternately interleaved. According to Fig. 6, corresponding to the four fingers of the right hand there are four strips (1 or 3) of a flat cable 4, and the strips of the corresponding left hand of the flat cable 4' to continue. To ensure contact, such interleaved (stacked) strips will be kept by an elastic clip 42 (not drawn) symbolized by the arrow force 28, (F). In a real case, the insulation of an insulated strip 3 of a flat cable 4 coming from the right will be partially stripped at its bottom (thus making the lead strip 1 accessible for electrical contact), while the lead strips of the flat cable 4' coming from the left will be stripped at the top, fig 6 A. By interleaving, the ends of the lead strips 1coming from right will connect correspondingly the lead strips coming from the left, whereby between the strips 1a, 1b, 1c and their counterparts 1a', 1b' and 1c', there is still an insulation remaining from the insulated strips (3). If necessary, you can insert an additional insulating film, even to make an additional function, for example, making only from the strips 1b, 1b 'a bifurcation 1b', 1b '', which can lead to a measuring device, switch, etc. Similarly (see Figure 6b), derivations can be made even without the interruption of the flat cable 4. Just strip (one or both sides) at the appropriate points of connection the insulation of the lead strips to be linked. The insulated strips 3 (1), 3 '(1') (1 with bare contact spots), that is the derivation will be inserted at the proper place (current path) under the corresponding lead strip and then the stacked contact areas, possibly after being supplementary insulated. The strip stack will be kept under pressure by an elastic clip 42, symbolized by the arrow representing the force 28 (F). It is clear therefore that this type of connection can be used for one or more derivations of one or more strips 1, 1 ', 1 "... 1n. These derivatives or extensions can be installed in almost any angle (0- 360 °) to the flat cable 4 coming. To achieve a good contact between all the strips 1, the entire "stack" of strip heads involved (from extensions or derivatives) will be kept under pressure, for example by a steel clip 42, (isolated from the strips 1) this applying a constant evenly spread pressure and on all the contact surfaces. There is no need for springs for each individual point of contact, as do the prior art. These extensions and derivations can be run in automated large series; the assembly is obviously simple, contact heads of the strips and clips 42 may be placed automatically, being dispensed in an expanded state; after mounting, the falling expanding parts are recovered to be reused. Maintaining this continuous and constant pressure is of utmost importance in the case of aluminium-aluminium contact because of the “settling” properties of pure aluminium, necessary for lead strips [1] (partial yielding in time, especially at higher temperatures). These contact zones, placed at extensions and bifurcations, can be protected (impregnated, covered) with various adequate insulating substances against chemical influences. Plug-socket connections will mainly be used to connect flat cable 4 technology to ordinary cables. We will mainly describe the construction of flat cable 4 plugs, with aluminium or copper lead strips 1. It is possible, and also recommended that these plugs be constructed starting with the welding (e.g. ultrasonic welding) of plug pins 27 (usually made from copper alloys), conveniently placed in space directly on the lead strips 1 (Fig. 7). Because of that we won’t describe other (more complicated) procedures for attaching flat cables 4, for example, to known plugs by screwing, soldering etc. According to Fig. 8, plug pins 27- 27a, … 27d, having a corresponding position to the socket to which they will be connected, are laterally welded (or soldered) on the insulated strips 3-, 3a, 3b, 3c and 3d of a flat cable 4. After the welding process, the end of the flat cable 4 with the welded plug pins 2], can be placed, for example, in an injection mould so that these elements will be embedded in a solid mass (or an a rubber- like one, for sealing elements) that will form the actual plug body 45 that has fastening and/or positioning elements (in this case a rectangular gap). The production of such plugs can be automated. In a special machine, the flat cable [4], advancing longitudinally, is cut and the ends of the insulated strips 3 are sufficiently separated so that the plug pins 27, which advance transversally, can pass between them. These pins are made in the same machine by cutting and rounding a continuous wire that is unwound from a reel. Usually, the lead strips don’t have to be stripped because the ultrasonic welding machine locally destroys the insulating foil 2. The subsequent cutting is advantageous because the uncut plug pins 27will be automatically and correctly positioned between the welding punches as they are extending from the correctly placed wire guides. The pins can be replaced with socket tubes, if the plug configuration demands it. The plugs can be built in the same way longitudinally, but the transversal position offers more opportunities. The ends of the flat strips 1 are really suitable to be worked out in linking parts of the current paths without separate plugs or plug bodies, as for instance seen in the Fig. 6 and 9. As shown in Fig. 9, the end of a flat strip1 can be formed out as a tube or a wire-like shape. Such a terminal tube can accept inside a plug pin, (this can also be made out of a lead strip) being this way the socket part of a plug. Such terminals can be made out with special pliers, which can if needed strip the insulation of he insulated strips 3, punch holes into them and turn their ends in forms according some of the terminal details as in Fig.9. Fig 12 shows how an in the plastic parts joining very common “slot and key” joint (it can belong to a housing, e.g. the “key” being on the lower part and the “slot” on the cover), which can be used supplementary as a plug joint, but without supplementary parts. On the left part “key” of the joint, an end of the lead strip 1 is put around, possibly stuck to it, it forms therefore the plug 46 of the plug joint. On the second right part “slot” of the joint, the end of the linking lead strip 1´ is put inside and also possibly stuck to it, it forms therefore the socket 47 of the plug joint. By joining the first and the second plastic parts, (left and right) “slot” and “key” will be assembled and also the plug 46 (with the lead strip 1) will come into electrical contact with the socket 47 (with the lead strip1´). No separate parts are needed, even more current paths can be connected, if these paths are formed by more lead strips, 1 (insulated strips 3) bonded parallel on the left and right plastic parts and placed upright to the route of the “slot and key”. This kind of plug/ socket without “own parts” can lead to considerable savings in the field of mass produced goods, e.g the HVAC- units of a car or the consumer goods industries. This way of joining can bring advantages also in the repair shop; just imagine the dismantling of an box- like apparatus, where both the (left and right) halves (one of them with the “key” closing line, the other with the “slot” counterpart) of the housing are carrying interconnected devices; by just opening the housing, the parts to be repaired will be available and automatically fully disconnected with less effort. Even switches or safety switches can be easier realised with the insulated strips 3. Just imagine an insulated strip 3, bonded on a support 5, which is a magnetic surface (iron sheet, as used in cars). Let us strip the foil 2 on the upper side and interrupt the lead strip 1 through a convenient gap. This gap can be shorted out by a small strip piece which can slide as a switch and/or be kept closed by a small magnet placed above it, which, due to the small thickness from the iron sheet up to the magnet (ca. 0,2…0,4 mm) will keep the contact firmly closed. If the magnetic forces are exceeded (due to the inertia) by an impact force (e.g. car crash), the magnet with the circuit closing strip piece will fall out and the circuit opens. The same can (once) occur, if the Curie point of the chosen magnet (e.g. 90°C) is overrun, so that the circuit opens due to the temperature rise. Another way to connect lead- 1 or insulated strip 3 is to clamp them between serrated pieces, which can scratch along the foils 2. Connecting the usual apparatus with flat cables 4 is also possible, but it is appropriate to design new electrical devices special for the use with flat cables 4 which will result in savings as well s an improved design. Like the flat cables 4, such apparatus can be low profiled, of a simple constitution and especially suitable to be bonded on walls and other supports 5, most sitting over the flat cables 4. It will be designed to be directly joined with cut out ends of the insulated strips (3) or lead strips 1. Home applications are especially interesting due to the usual need of completing or extending an electrical installation that stick on the floor, under the carpet, on the walls etc., with no need to dig special channels in plaster or concrete. Especially in small successive upgrades, like small electric automations for windows, radiators, or signal systems (alarms), it’s necessary to fit hidden conductors, even for voltages as high as 36V. The insulated strips 3 and flat cables 4 are ideal for this purpose. The construction variant C (Fig. 4) for usual lines up to 16 A has the lowest thickness, under 1 mm, including the mounting adhesive 14. Stuck to the wall and covered by wallpaper it will be practically invisible. In every home or industrial power network, a conductor (according to the invention the insulated strip 3N) is connected to the 0 potential and is called null lead (N). The other lead strip (more strips in having more phases) is called phase lead, here called F so that the insulated strip will called as 3F. Another 0 potential lead is “grounded”, being the protection null and called as P. We will use the letters N, F and P as attributes of the lead strips 1 and insulated strips 3 of the flat cables 4. The flat cables 4 can be perfectly concealed and they are remarkably safe due to the fact that the phase insulated strips 3F will always be protected under an insulated strip 3P with 0 potential. Subsequently it is mandatory that the strips 3P (protection null) will be placed on the outside (relative to the support 5) for all production variants to insure people’s safety. Fig. 9 shows examples how the ends of lead strips are worked out for, to be accepted by usual sockets and existing appliances (outlets, switches, etc.) with clips or screws. To go up to these devices, simple and/or double folds 25 can be made, these not being limiting examples. Due to the multitude of folds we are limiting ourselves to a few graphical representations. Existing appliances can be normally placed on the wall or buried. In both cases, the covers of these appliances will be placed over the wall mounted flat cable 4 in the area in which it wasn’t stripped for connection. The insulated strips 3 contact areas will be stripped and additionally protected or fixed with insulating tape. To implement the function of a fuse on the lead strips 1 their cross- section can be reduced by partially reducing the width, for example by punching a hole. This reduced section will melt when overloaded, breaking the circuit. This melting area must be placed between two fireproof layers. In order to help electricians to take profit of this invention, tool and accessories kits should be provided for the specific tasks in homes and industry. They can for instance contain insulation strippers, pliers, adhesive tubes with special one-way dispensers, adhesive and masking tapes, adapter devices for linking with common lines, specific apparatus, etc.

Vehicle applications: The wire harnesses of cars, planes, ships etc. consists of long, ready to mount cables which are fixed on a support (body of vehicle) with only their final part needing possibly flexibility. However these parts are still wholly made out of flexible stranded cables having an important cross- section and weight. With aluminum conductors, their lower electrical conductivity with respect to copper, leads to an increase of about 60% in the cross- section to keep the electrical characteristics. Despite the increase of metal cross-section the aluminium cable will be more than 60% lighter and thinner as previously seen. Lead strips made out of anodized aluminium with a very thin additional insulation can be used for heavy duty working conditions, where they won’t short-circuit even if the insulation foil 2 melts. Main power lines, made out of flat cables 4 or groups of flat cables 4 as wire harnesses for planes, cars and ships, will have to be redesigned. It’s recommended that these lead strip harnesses would be used only where they can be stuck to the vehicle body and end in fixed connector boxes 30. The flexible connections will begin there. Therefore, the connections from the connector boxes 30 to various mobile or vibrating units (e.g. doors, moving lids, alternator, etc.) will be made using known flexible cables. According to the invention, by using aluminium for the power harness, aluminium-copper connections will be necessary. It is not a problem to make these with modern technical means (ultrasonic welding, using bimetal aluminium-copper parts etc.). Sometimes, especially in humid or chemically influenced mediums, these Cu-Al connections will have to be protected against corrosion with known methods. It is necessary for this technology too, that the number of connections (plug-socket) remain as low as possible. With the new connector boxes 30, other connectors can be removed. Sub- assemblies will be designed differently (e.g. the plug won’t be on the alternator, but on a flexible cable that goes from the alternator to the connector box 30). The plug is placed in the connector box 30 instead of being placed on the alternator. This will have finally positive results, the mounting being easier and automatable. On a car chassis, the connector boxes 30 can be directly deep-drawn into the metal sheet of the body. The flat cables 4 can too be placed in embossed ribs, especially drawn in the metal sheet of the car body (possibly covered with point welded strips of metal sheet) which leads to space saving and improved stiffness. The major part of the electric harness of a car, plane etc. can be made according to this invention from aluminium with important savings in price and weight. As seen above, the cross- section of a flat cable 4 with 20 lead strips 1 made out of aluminium is less than half that of the round copper cable it replaces having the same electrical properties. The reduced cross- section of the new flat cable 4 power harnesses on fighter planes makes it easier to armour them (e.g. by placing them in a titan armour) to better resist bullets and splinters. The clatter of the cabling is greatly reduced due to them being glued along with viscous- elastic materials on the entire surface, which reduces the risk of wear and short-circuits in the harness. The flat cables 4 can be also used otherwise, for the subsequent extension of wire harnesses in vehicles. Because of the self- bonding principle, the flat cables, often under 1 mm thick can be easily placed and hidden on various supports 5 (chassis, floor, under the rug, on the walls of an utility car, to additional headlights or devices).

Cable making machines. Fig. 10 shows the principle of a machine for making the insulated strip 3, according to the working principle represented in Fig. 2. Mounted on a convenient support (not drawn) are: the supply reel 31 (reels) for the lead strip1 which is led by the guide 32 and the foil supply reel 33 for the insulating foil 2. A dispenser 35 supplies the necessary inside adhesive 15. A guide 32 for the foil 2 places it around the lead strip(s) 1. The welding channel 36 thermally welds the foil 2. The drive rollers 34 maintain the constant speed necessary for the process. The insulated strip 3 goes through the heat channel 37 which shrinks the foil 2 around the lead strip 1 and hardens (partially) the inside adhesive 15. The insulated strip 3 can be cooled in the heat sink 38. A marking wheel 39 can also be added before the insulation is spark- tested with high voltage electrodes 41 placed around the insulated strip 3. They are linked to a signal device which reacts if an abnormal current arises. The insulating strip 3 is then wound on a collector reel 40. In order to enclose more complex flat cables 4 or bundles of flat cables, a machine working in principle as above described will be needed. Due to the bigger, sometimes less regular cross- sections of the cables to be enclosed, however, some changes of the machine must be done: the guide 32 should be adapted to accept bigger, less regular cross- shapes. For this, it can have elastic elements, such as guide- brushes, which can mould the foil 2 close around to the bundle of cables. As the edges of the foil 2 cannot perfectly fit every extent of the cables bundle, it will be necessary to bring them together by a special guide and to cut the exceeding part of the edges of the foil 2 by supplementary scissors, placed just before the welding channel 36 so that they can be properly welded. Changes of the machine details for more particular purposes are possible.

Other applications: Aside the before listed applications, many others are also possible, as:

-Windings for motors and transformers, (often out of aluminium)

-Windings for induction cookers (aluminium replaces copper)

-Flat cables, embedded into composite materials (boats, wind turbines)

-Heating lines for piping and plumbing,

-dissimulated stuck antennas.

Claims (1)

1) Flat insulated strips for flat electrical cables with medium cross- sections of the single conductors, insulated with thin foils of plain insulating material, for the distribution of low voltage electrical power, with use in home, industrial and vehicle- borne electrical networks, being preferably bonded on supports, characterized in that these flat cables (4) have reduced cross-sections at the same electrical conductivity as the state-of -the-art cables and are made from the insulated strips (3) which result from flat metal lead strips (1) surrounded with very thin insulating foils (2) as a continuous sealed layer achieved by continuous longitudinal welding (17), made by contactless melting and joining the foil (2) edges with thermal effect radiation so that the resulting insulated strips (3) don't have thickenings caused by overlapping them for or welding.

2) Insulated strips 3, according to the claim 1 characterized in that the insulating foils (2) have thermoplastic properties.

3) Insulated strips 3 according to the claim 1 characterized in that the insulating foils (2) are stuck to the lead strips (1) by an inside adhesive (15).

4) Insulated strips 3 according to the previous claim 1 characterized in that the insulating foils (2) are covered with antistatic layers.

5) Insulated strips 3 according to the previous claim 1 characterized in that the insulating foils (2) do have shrinking properties.

6) Insulated strip 3 according to the previous claim 1 characterized in that the insulating foil (2), more than half as wide as the lead strip (1), is placed with suitable guides adjacent to the lead strip (1) so that the edges of the foil (2) come close and in this position they get locally heated and melt by thermal radiation so that they become welded together by touch.

7) Insulated strips 3 according to the claim 1 characterized in that they are made by simultaneous insulating some parallel metal lead strips (1) that are guided side by side on the same plane, with an intermediate space (18) between the edges, they being placed between two insulating foils (2a, 2b), whereby the foils (2) get welded together around the lead strips (1) through multiple welding seams which arise by simultaneous passing the lead strips (1) and the foils (2) in front of sources of radiation (21).

8) Insulated strips 3 according to the claim 7 characterized in that a radiation absorbent stuff (22) is dispensed on the surfaces foil (2) in the areas which will be welded.

9) Flat cables 4 made from insulated strips (3) according to the previous claims, characterized in that the insulated strips (3) are placed together and assembled in the form of a flat cable (4) through gluing, wrapping with other foils, enclosing them in a tube or embedding them in a semi-rigid mass of intermediate adhesive (24).

10) Flat cables (4) according to the claim 9 characterized in that their fixing on a support (5) like a wall, the body of a vehicle, etc. is achieved by sticking with mounting adhesives (14), preferably self-adhesive layers, dispensed from manufacturing or in the form of paste applied between the flat cable (4) and the support (5) right while they are fitted.

11) Flat cable 4 according to the claim 9 characterized in that it consists of insulated strips (3a, 3b…) placed side by side, glued on a non-insulated (1) or insulated strip (3) wider than all the insulated strips (3a, 3b…) put together, their assembly <insulated strips (3a, 3b…) and wider non-insulated (1) or insulated lead strips (3) > being provided on the side to be bonded on a support (5) with a mounting adhesive (14), as in Fig. 4.

12) Flat cables 4 made from insulating strips 3 according to the claim 9 characterized in that for fixing them on a support (5) these flat cables (4) and their branches (4', 4'') or insulated strips (3) will be placed in the required direction by simple (25) or double (26) folding and subsequently glued to the support (5).

13) Method of connecting more flat cables 4 and insulated strips 3 to further circuit parts according to the claims 1 and 9- 12 characterized in that the insulated strips (3), with the insulation stripped in the places to be put in contact, the lead strips (1) forming by interleaving contact zones for different potentials, and that these contact zones are insulated between them, possibly by additional insulating foils and stacked together in such a way that a clip (42) can insure the necessary contact pressure for all the contact points of the involved current paths.

14) Plug for linking flat cables 4 and insulated strips 3 to further circuit parts according to the claims 1 and 9-12 characterized in that conveniently placed plug pins (27) are welded to the insulated strips (3) or the lead strips (1), which, after welding, are going to be placed according to the shape of the socket in positions corresponding to this part, the plug pins (27) being subsequently embedded in an insulating material which becomes the plug body (45).

15) Plug for linking flat insulated strips 3 according to the claim 1, characterized in that the plug (46)- and socket (47) parts of this link are constituted by the end of insulated strips (3, 3´) which are molded and stuck on plug (46), and socket (47) protrusions, these being only forms of a more complex device which must be mounted together, so that by mounting the device the plug (46), and (47) protrusions with the correspondingly insulation stripped ends, i.e. the lead strips (1, 1`) of the insulated strips (3, 3´) will come into electrical contact and constitute a plug joint which does not need any own parts.

16) Switch for connecting insulated strips 3 according to the claim 1, characterized in that the one- side stripped ends of the lead strips (1, 1´) of two insulated strips (3, 3´), stuck on a magnetic support (5) are being conditionally shorted out by a movable shorting strip piece which keeps the shorting contact closed by the force of a permanent magnet being pulled by the support (5) the contact being opened by an external force, i. e. by hand or shock (inertia) or by a temperature exceeding the Curie- point of the permanent magnet.

17) Flat cables 4 for home electrical networks according to the claims 1 and 9- 12 characterized in that they are made from insulating strips (3) these being null insulated strips (3N), phase insulated strips (3F) and protection null insulated strips (3P), the latter being placed at outside with respect to the support (5).

18) Flat cables according to the claim 17 characterized in that, to be connected to bifurcation boxes and existing appliances (outlets, switches etc.) the constituent lead strip (1) terminals will be shaped through axial and/or length folding, rolling them in shaped tube, pressing (crimping), punching, through addition of auxiliary pieces etc., to get forms that can be entered directly into the connection of existing apparatus as seen in Fig. 9.

19) Power strip harness with flat cables for vehicles with round structures according to the claim 1 characterized in that insulated strips (3) or flat cables (4) are bonded on essentially curved supports (5) and that they are being bent and bonded to follow the shape of these supports (5).

20) Power strip harness with flat cables for vehicles according to the claims 1 and 9- 12 characterized in that it is composed of two zones, one fixed on the support (5), made from aluminum flat cables (4) and a second zone consisting of usual flexible cables connected through plugs (29) to the first fixed zone.

21) Power strip harness with flat cables according to the claim 17 characterized in that it is composed from a multitude of aluminum insulated strips (3) placed in a main bundle made out of flat cables (4), which split as needed into flat cable (4', 4'') branches, the insulated strips (3) being held together as a main harness with outgoing branches by wrapping with foils or enclosure in tubes out of thermoplastic foils, made out by length welding, which can be subsequently thermally shrunk to firmly hold the insulated strips (3), creating thus flat cable (4) parts of appropriate shapes according to the specification out of the multitude (n) of insulated strips (3) of a main flat cable (4), this being the main harness.

22) Insulated strips and/or flat cables thereof according to the claim 1 characterized in that they are bonded on supports (5) made out of materials with good heat sinking properties so that the heat which arises in their flat leads (1) is essentially lead to the support(s) (5) which prevents the overheating or the failure of the flat cables (4) .

23) Insulated strips and/or flat cables thereof according to the claim 1 characterized in that they are bonded on supports (5) principally made out of metal sheet with appropriate adhesives, so that they constitute together with the supports (5) noise deadening, sandwich- type structures in order to reduce the drumming of the supports (5).

24) Power strip wire harness with flat cables according to the claims 14 and 20 characterized in that the branches of the flat cable (4', 4'') or the entire main strip harness end with plugs (45, 29) or socket connection zones preferably placed in connector boxes (30), fixed on the same support (5) as the main harness (4, 4',4'').

25) Machine for manufacturing an insulated strip according to the claims 1- 6 characterized in that it operates continuously with the tapes and foils driven by the collector reel (40) and the drive rollers (34), the insulating strip (3) being successively composed through unfolding of the foil (2) on which an inside adhesive (15) can be applied by a dispenser (35) the foil (2) being placed aside the lead strip(s) (1) through the foil guide (32), the lead strips (1) and the foil (2) passing successively through the welding channel (36), the thermal channel (37) and the heat sink (38), according to Fig. 10.

26) The machine according to the claim 25, characterized in that the spark test is made by passing the insulated strip (3) through high voltage electrodes (41) connected to a signal device that reacts to the occurrence of an abnormal current.

27) Insulated strips (3) according to the claims 1 and 3- 6 characterized in that a foil (2), which can't be welded through direct heating, is bonded along to cover a lead strip (1) through the addition of substances that lead to the forming of a sealed closing seam.

28) Electrical apparatus for home appliances to be connected with flat cables according to the claim 1, characterized in that they are designed to be joined with cut ends of the insulated strips (3) or lead strips (1) and that they are fitted by bonding on supports (5), for instance walls, panels, etc…